We are proposing an urgent competitive revision for our current grant (R01DA04686702) to study the impact of the novel coronavirus (COVID-19) pandemic on syringe service programs (SSPs) throughout the United States (US). The COVID-19 pandemic has rapidly proliferated and caused unprecedented disruption to health and health services in the US and has the potential to reverse recent reductions in the nation's opioid overdose mortality rate. As cities, counties, and states tried to stunt the transmission and impact of COVID- 19, they began rolling out various social distancing orders (e.g., Shelter-in-Place). A consequence of these public health mandates and the need to protect people from COVID-19 has been disruptions in services for people who inject drugs (PWID). Particularly in the context of the opioid epidemic, understanding how the COVID-19 pandemic has affected services for people who use drugs is critical to know how to respond within the current pandemic and to be better prepared for future public health crises. SSPs have been the mainstay for community-based prevention efforts for PWID and have pioneered efforts for implementing overdose education and naloxone distribution (OEND) and improving enrollment into medications for opioid use disorder (MOUD) programs. SSPs are considered an ?essential service? and have not been mandated to suspend services during Shelter-in-Place orders. As part of our nationwide study of SSPs, our study team has documented that SSPs are facing unprecedented challenges and adapting implementations, as necessary. Leveraging our ongoing study, we propose to build a comprehensive understanding of adaptations made in response to COVID-19. Using the exploration, preparation, implementation, and sustainment (EPIS) framework, we propose to systematically assess the impacts of the COVID-19 pandemic on SSP services in the US. Our proposed aims are as follows: Aim 1: To characterize the response to COVID-19 regarding the delivery of syringe services, overdose education and naloxone distribution, and medications for opioid use disorder among SSPs; Aim 2: To describe barriers and facilitators among SSPs regarding implementation of syringe services, overdose education and naloxone distribution, and medications for opioid use disorder during the COVID-19 pandemic. To achieve these aims, we will conduct a cross-sectional study with all SSPs (N = 407) in the US in late summer/fall 2020. In addition, we will conduct in-depth interviews with 36 SSPs from geographically diverse urban, suburban, and rural locations where we observe varying levels of implementation experiences?de-implementation of services, adapted implementations, and implementation as usual?during the COVID-19 pandemic. Understanding how the COVID-19 pandemic has impacted services for PWID is critical for improving our response within the current pandemic and being better prepared for future pandemics.